The present invention relates to a power converting apparatus, control method therefor, and power generation system.
Recently, home solar power generation systems which combine a solar battery of several kW to several ten kW and a power converting apparatus (voltage inverter) for converting DC power generated by the solar battery into AC power are proliferating.
A voltage inverter for converting DC power into AC power generally has a smoothing capacitor at the input section of the inverter main circuit. When the smoothing capacitor degrades, the electrostatic capacitance becomes low, resulting in an increase in ripple component of the DC current or voltage across the terminals of the smoothing capacitor. Hence, when the ripple component of a smoothing capacitor is detected, the service life of the smoothing capacitor can be determined, as disclosed in Japanese Patent Laid-Open No. 7-222436.
A conventional inverter is controlled such that upon detecting a degradation in smoothing capacitor, the operation of the inverter is stopped, and the resumption of the operation is inhibited until the degraded smoothing capacitor is exchanged.
In a solar power generation system having the above-described inverter, when the smoothing capacitor of the inverter degrades, the operation of the inverter is interrupted until the capacitor is exchanged. For this reason, some loss in amount of the power generation occurs inevitably in the solar power generation system.
The present invention has been made to solve the above-described problem of the prior art, and has as its object to provide a power converting apparatus, control method therefor, and power generation system, which can continue appropriate operation even when a smoothing capacitor degrades.
In order to achieve the above object, the present invention has the following arrangement.
That is, there is provided a power converting apparatus having a capacitor, comprising degradation determination means for determining a degradation in capacitor, and output suppressing means for, when the degradation determination means determines the degradation in capacitor, suppressing a maximum output value in the power converting apparatus.
For example, the output suppressing means preferably repeats suppression in units of predetermined suppression amounts until the maximum output value becomes not more than a predetermined value.
For example, when a sum of suppression amounts of the maximum output value exceeds a predetermined value, the output suppressing means preferably stops output of the power converting apparatus.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.